The present invention found its origin in so-called masonry cavity wall constructions. Masonry cavity walls have inner and outer vertical walls. The inner wall is typically constructed from wood with an inner surface of drywall, structural clay tile, vertical stacks of mortared bricks, or a shear concrete surface. The stacks of bricks that are held together by mortar. A space, or cavity, exists between the two walls, which may be partially filled with insulation. It is applicant's understanding that the Brick Institute defines a "cavity wall" as having a space greater than about 2 inches but not more than 4 inches between the masonry wythes.
A crack in the wall can allow water to enter the cavity. More often, however, moisture can condense on the inside of the wall under changing temperatures. Either way, water may collect in the cavity between the inner and outer wall.
The presence of moisture in the space between the inner wall and outer wall is undesirable for a number of reasons. First, the trapped moisture can degrade the inner and outer wall, causing a weakening of the structure. Second, the presence of water under freezing temperatures may also cause cracks in the walls when the water expands as it freezes. Trapped water in the cavity between the inner and outer walls may cause the walls to become discolored, and may even leak into the dwelling.
To overcome the problems associated with water trapped within a masonry cavity wall, weep holes are commonly placed along the base of the outer wall. The weep holes allow water to pass from the cavity to drain outside the wall structure.
During construction of a masonry cavity wall, excess mortar and other debris can and does fall between the inner and outer wall. When the bricks are stacked during the erection of the outer wall, for example, mortar droppings are squeezed into the space between the walls. The excess mortar, as well as other debris, drops to the base of the cavity, and can block the weep holes.
Wicks have been used in weep holes. For instance a cotton wick, such as a segment of cotton rope, has been used in weep holes. Such wicks can be extended from the weep hole up within the cavity to a height considered sufficient to exceed any build-up of mortar droppings. Moisture within the cavity is absorbed by the wick, and passed to the outside face of the wall. Wicks are preferably made from cotton, because nylon or hemp are considered less efficient in transferring water. The cotton wick, however, may become broken or squashed, and will rot with time. Accordingly, the weep hole may still become blocked during and after construction, thereby preventing moisture in the cavity from passing to the outside of the wall.
Another attempt to overcome the problems associated with obstructed weep holes is described in U.S. Pat. No. 4,852,320. The '320 patent describes embodiments of a mortar collection device located in the wall cavity. One embodiment is adapted to collect mortar but deflect water. This mortar collection device has an upper surface with sufficient inclination to cause moisture to slide off, but is purportedly insufficiently inclined to prevent mortar from falling off. A second embodiment has a plurality of vertically aligned passageways of dimension sufficient to allow moisture to pass therethrough, but of insufficient dimension to allow mortar to pass therethrough. This honeycomb-like mortar collection device of the '320 patent is made from a non-water absorbent material, such as plastic.
It can be seen, nonetheless, that mortar or other debris may still roll down the surface of one or more of the collection devices of the '320 patent and plug a weep hole. Also, the '320 patent mortar collection devices are specially adapted to be carried on reinforcement rods extending between the inner and outer wall. They are not shown adapted to simply rest on the base of the wall, so as to completely cover the weep holes. Furthermore, in the second embodiment of the '320 patent described above having the vertical passageways, small pieces of mortar on other debris may still pass through the holes extending through the unit, thereby allowing the debris to reach the base of the wall and plug the weep holes.
It would be desirable to have a mortar and debris collection device capable of resting on the base of the wall in the space between the inner and outer walls to cover and protect the weep holes, as well as being supportable at different heights on the wall without the use of any additional fixation device or special attachment design feature. Furthermore, a collection device should prevent mortar droppings and other debris of any appreciable size from reaching the weep holes.